JPS60186790A - Nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention provides a system for sending cooling air inside a reactor pressure vessel to the core using an in-core circulation pump provided outside a core shroud in the reactor pressure vessel. Concerning the improvement of nuclear reactors.

[Prior art and its problems]

The lower structure of a conventional nuclear reactor will be explained based on FIG. 1, taking a boiling water reactor as an example.

Several in-core circulation pumps 4 are installed in the lower part of the reactor pressure vessel 1, and the reactor pressure vessel 1 and the core shroud 2
The coolant 3 descending through the downcomer between the reactor core 5 and the reactor core 5 is circulated and supplied to the reactor core 5 by the circulation pump 4 . Circulation pump 4
The coolant 3 pressurized by this flows into the core lower plenum 81 from the gap between the core shroud 2 and the pressure vessel lower mirror 6, and
After colliding with the reactor internals 7, the flow becomes an upward flow toward the upper part of the core.

Conventionally, the inlet to the lower blenheim 8 is connected to the core shroud 2.
It is constructed as shown in FIGS. 2 and 3 from a structure 9 (hereinafter referred to as a shroud support leg) that connects the shroud support leg to the bottom of the pressure vessel @6, and an opening 11 thereof.

However, in the shroud support leg 9 configured as shown in FIGS. 2 and 3, the flow discharged from the circulation pump 4 collides with the shroud support leg 9, causing thinning, resulting in pressure loss. There is a concern that the flow of coolant in the lower core plenum may become large, disrupting the flow of coolant in the lower core plenum, and the resulting vortices colliding with structures, adversely affecting the integrity of the structures in the lower core plenum.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned circumstances, and provides a shroud support leg that reduces pressure loss to the coolant discharged from the circulation pump and does not significantly disturb the flow of coolant in the lower core plenum. The purpose is to provide a nuclear reactor with

[Summary of the Invention] The present invention provides a structure in which, in a shroud support leg that connects a reactor core shroud and a reactor pressure vessel, the cross-sectional shape of the coolant discharged from the circulation pump in the flow direction disturbs the streamlines of the flow of the coolant. This is a nuclear reactor with shroud support legs made in a unique shape.

〔Effect of the invention〕

According to the present invention, since the coolant discharged from the circulation pump collides with the shroud support leg and no soot is generated, the pressure loss at the shroud support leg can be suppressed to a low level. Since it is possible to lower the specifications for the total head of the pump, it is possible to operate the pump at a lower rotation speed, which is expected to improve the safety of the entire plant.

Furthermore, since no major turbulence occurs in the flow of coolant in the lower core plenum, no large fluid force is applied to the structures in the lower core plenum, thereby improving the safety of the structures.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 4 and 5 are explanatory diagrams illustrating the horizontal cross-sectional shape of the shroud support leg, which is the object of the present invention, the pump, and the flow of coolant into the lower core blenum.

The shroud support leg shown in FIG. 4 has a cross-sectional shape on the side that collides with the coolant so that the edge thereof forms part of a circular arc. The shroud support leg with the above shape has a much smaller drag coefficient than the conventional shroud support leg whose edge has a rectangular cross-sectional shape as shown in Figure 2. Low pressure loss. The thin layer formed in the wake of the trench is also small. In addition, the shroud support leg shown in FIG. 5 has a front surface (pump side) that is part of an arc or an ellipse,
The shape of the rear surface (lower core Blenheim side) is a shroud support leg with a smooth curve connected to the trailing edge. Similar to the shroud support leg shown in FIG. 4, the shroud support leg having the shape as shown in FIG. 5 has a small pressure loss on the coolant and can lower the specification of the total pump head. In addition, the shroud support leg having a shape as shown in Fig. 1g5 has a large rectifying effect on the flow downstream of the leg, and can avoid applying a large fluid force to the structure in the lower core plenum.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing the lower structure of a conventional boiling water reactor, and Figures 2 and 3 are schematic diagrams showing the shape of the shroud support leg of a conventional boiling water reactor. , FIG. 4, and FIG. 5 are schematic diagrams showing an embodiment of the present invention. 1... Reactor pressure vessel 2... Core shroud 3.
...Core coolant 4.In-reactor recirculation pump 5..Reactor core 6..Pressure vessel lower mirror 7..Internal structure 8..
・Lower core shroud 9...Shroud support leg 10...Pump deck 11...Shroud support leg opening representative Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure '21 Tsu 1 Figure 3 tr tl //muth (. η Zozoshin/ )

Claims (3)

[Claims] (1) An in-reactor circulation pump is provided outside the core shroud in the reactor pressure vessel, and the above-mentioned circulation pump is A number of structures are installed downstream of the coolant discharge port to align the shroud with the lower mirror of the reactor pressure vessel.
A nuclear reactor characterized in that at least a part of the cross-sectional shape of the structure in the coolant flow direction is arcuate. (2) At least part of the horizontal cross-sectional shape of the downstream surface of the structure that connects the core shroud and the lower head of the reactor pressure vessel, which is on the lower core plenum side, is an arc or an ellipse. The nuclear reactor according to claim 1, characterized in that: (3) At least one part of the horizontal cross-sectional shape of the surface of the structure that connects the core shroud and the lower mirror of the reactor pressure vessel that collides with the coolant discharged from the reactor circulation pump, which is the reactor circulation pump side. The nuclear reactor according to claim 1, wherein the portion is a part of a circular arc or an ellipse.